This invention relates to methods and apparatus for manufacturing rectangular frames for doors.
The manufacture of doors for houses, office buildings, and other structures has long been handicapped by the need for virtually total manual assembly of the door frames. In a typical door manufacturing process, rectangular frames of standard sizes are manually assembled from wooden vertical members or stiles and wooden horizontal members or headers. A core, usually of lightweight filler material, is inserted within the rectangular frame, and then inner and outer surfacing materials such as plywood are laminated over both sides of the frame and filler. Thereafter, a door knob, lock, and other desired attachments may be installed to complete the door.
Automation of the assembly of many prefabricated building components such as walls, floors, ceilings, and the like, has been attempted for many years. It has been possible to partially automate the manufacturing steps for some prefabricated building components, albeit with varying degrees of success. Even in the manufacture of doors some automation has been achieved in the steps of installing filler materials and surface laminates to door frames. However, the assembly of the door frame itself has heretofore defied all attempts to employ a continuous, automated manufacturing process. Not only has much expensive manual labor been required in making frames, but also non-uniform structures with improperly aligned stiles, headers, fasteners, or all of these, are sometimes produced due to human error, fatigue, and the like. The manual production of door frames also creates a serious bottleneck in what otherwise might be a relatively speedy door-making process.
Even when attempts are made to speed up the manual construction of door frames, for example, by using preset jigs for aligning the boards which make up the stiles and the headers of the frame, such attempts are only partially successful. This is due to the fact that for each given arrangement of apparatus, generally only one type of frame can be produced. Preferably, door frame-making apparatus should be capable of being adapted to use boards, i.e., stiles and headers, of various lengths, widths, and thicknesses without any appreciable time delay. It is especially desirable that door frame-making apparatus be capable of automatically adjusting itself to make any width of door without any operational changes by the operators, except, of course, to use different sizes of headers in the frame.
It is also desirable to have a fully continuous feeding operation to initiate the construction of each door frame without the necessity for manually starting the sequence. In other words, the human element should be simply to respond to the needs of the automated machine rather than to initiate each sequence, since any requirement for human intervention to start each sequence will necessarily result in time delays, depending on the self-discipline of the operator and other human variables.
Still another problem with prior art techniques is the need for special manual steps for fastening one or more lockblocks to the frame. When a doorknob, or a lock, or both, are to be installed, the frame stile itself generally is not wide enough to support such devices. To allow for the knob and lock to be installed thus requires that a short wide board or lockblock be secured inside the frame adjacent to the stile at the height where the knob and lock are to be positioned. This has heretofore required distinct manual installation and fastening steps which have added to the time consumption and potential for human error in placement or fastening of the lockblock to the stile. Moreover, since many doors are initially constructed without any knob or lock, and the decision is left to the user which side to install such devices on, it is often necessary to include lockblocks along both stiles. In the prior art techniques, this required still more manual steps with their attendant disadvantages.
Another problem with the prior art techniques for manufacturing door frames is in the variable placement of the fasteners, usually staples, which hold members of the frame together. if the staples are positioned too close to the top of the upper header, too close to the bottom of the bottom header, or too close to the outer edges of either of the stiles, this can cause problems after the door is fully assembled and the fasteners are covered up. For example, if it becomes necessary for the user to trim the ends or sides of the door by sanding it or sawing off an edge in order to install it, the sanding or sawing operation may be frustrated by encountering the misplaced staples. Thus, it would be highly desirable to provide the art with a method whereby human error in installing fasteners could be eliminated and the fasteners could be uniformly and consistently inserted in the frame at a precise distance as close to the inner edges of the stiles and headers as possible.
It is also desirable to provide a machine suitable for high speed door frame production while allowing for a variation in speed of human participation depending upon the size and weight of materials being manually handled and the state of fatigue of the operators. Thus, it would be desirable to provide a high speed process where all the steps of the operation are coordinated with each other yet permit speeding or slowing of the whole operation depending on the capacity of the operators to respond to the machine steps.
To achieve the foregoing and other goals, and to eliminate or lessen the problems of the prior art, are the objectives of this invention.